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SECTION 6-2 REVIEW
T HE C ALVIN C YCLE
VOCABULARY REVIEW Define the following terms.
1. Calvin cycle
2. carbon fixation
3. stoma
4. C4 pathway
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5. CAM
MULTIPLE CHOICE Write the correct letter in the blank.
1. The Calvin cycle begins when CO2 combines with a five-carbon carbohydrate called
a. RuBP.
b. PGA.
c. PGAL.
d. NADPH.
2. For every three molecules of CO2 that enter the Calvin cycle, the cycle produces
one molecule of
a. RuBP.
b. PGA.
c. PGAL.
d. NADPH.
3. Organic compounds that can be made from the products of the Calvin cycle include
a. only carbohydrates.
b. only amino acids.
c. only lipids.
d. carbohydrates, amino acids, and lipids.
4. C3 and C4 plants differ in terms of the number of
a. steps in the Calvin cycle.
b. carbon atoms in the compound that
CO2 is initially incorporated into.
c. carbon atoms in the end product of the
Calvin cycle.
d. ATP molecules used in the Calvin cycle.
5. As light intensity increases, the rate of photosynthesis
a. continues to decrease.
b. continues to increase.
c. initially decreases and then levels off.
d. initially increases and then levels off.
Modern Biology Study Guide
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SHORT ANSWER Answer the questions in the space provided.
1. How many molecules of ATP and NADPH are used in each turn of the Calvin cycle?
2. Using (CH2O) as the general formula for a carbohydrate, write the simplest overall equation for
photosynthesis.
3. How do CAM plants differ from both C3 and C4 plants?
4. Why does the rate of photosynthesis increase, peak, and then decrease as temperature increases?
5. Critical Thinking Stomata can open and close in response to changes in the CO2 concentration
inside the leaf. Would you expect stomata to open or close if the CO2 concentration decreased?
Explain.
The diagram below summarizes the Calvin cycle.
CO2
RuBP
ADP
ATP
PGA
ATP
ADP
PGAL
NADPH
NADP1
34
Section 6-2 Review
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STRUCTURES AND FUNCTIONS In the blank spaces provided in the diagram, indicate
the number of molecules of each substance that are involved in each turn of the cycle.
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2. Carrier proteins bind to a molecule of the substance on one side of the membrane, change
shape, transport the molecule across the membrane, and release the molecule on the other side.
3. The stimuli are stretching of the cell membrane,
electrical signals, and chemicals in the cytosol or
external environment.
4. Both involve the binding of a specific substance to
a particular kind of protein and a change in shape
of the protein as the process (transport or chemical reaction) proceeds. After the process is completed, the protein is unchanged.
STRUCTURES AND FUNCTIONS
1. a, hypotonic; b, hypertonic; c, isotonic;
d, hypertonic; e, isotonic; f, hypotonic
Section 5-2
VOCABULARY REVIEW
1. Active transport is the movement of materials
across a membrane from an area of lower concentration to an area of higher concentration.
2. Endocytosis is the process by which cells ingest
external fluid, macromolecules, and large particles.
3. A vesicle is a membrane-bound organelle that
pinches off from the cell membrane during
endocytosis or fuses with the cell membrane
during exocytosis.
4. Phagocytosis is a type of endocytosis in which
cells ingest large particles or whole cells.
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MULTIPLE CHOICE
1. b
2. a
3. c
4. b
5. d
SHORT ANSWER
1. The mechanism uses energy to move Na1 and K1
up their concentration gradients.
2. The phagocyte forms a pouch in its cell membrane
and engulfs bacteria in the pouch. It then pinches
off the pouch to form a vesicle. Lysosomes fuse
with the vesicle, and lysosomal enzymes destroy
the bacteria it contains.
3. Proteins are made on ribosomes and packaged into
vesicles by the Golgi apparatus. The vesicles move
to the cell membrane and fuse with it, releasing the
proteins from the cell through exocytosis.
4. The interior of the lipid bilayer is nonpolar and
therefore would repel ions, which are attracted to
polar environments.
STRUCTURES AND FUNCTIONS
1. The correct order is d, c, f, b, a, e. 2. Na1 ions are
released on the external side of the cell membrane. 3. K1 ions are released on the cytosolic
side of the cell membrane.
Section 6-1
VOCABULARY REVIEW
1. Grana are stacks of thylakoids inside a chloroplast; the stroma is the solution that surrounds
the thylakoids.
2. Accessory pigments assist chlorophyll a in capturing light energy during photosynthesis.
3. Chemiosmosis is the process by which ATP is
made during photosynthesis. The production of
ATP is catalyzed by the enzyme ATP synthase.
MULTIPLE CHOICE
1. a
2. c
3. d
4. b
5. c
SHORT ANSWER
1. Photosynthesis involves many chemical reactions
linked such that the product of one reaction is
consumed in the next reaction.
2. Chloroplasts have an inner membrane system consisting of thylakoids. The pumping of protons into
the thylakoids builds up a proton concentration
gradient across the thylakoid membrane.
3. The energy-carrying products are ATP and NADPH.
4. They help chlorophyll a capture light energy by
absorbing energy in wavelengths that chlorophyll
a cannot absorb. This enables the photosynthetic
cell to capture more of the energy in light.
5. Photosystem II most likely evolved first, because it
replaces electrons lost from chlorophyll a with
electrons from water. Since photosystem I accepts
electrons from photosystem II, it probably evolved
after photosystem II.
STRUCTURES AND FUNCTIONS
a, electrons; b, NADPH; c, ATP; d, H1
Section 6-2
VOCABULARY REVIEW
1. The Calvin cycle is a biochemical pathway that
produces organic compounds from carbon dioxide
during photosynthesis.
2. Carbon fixation is the incorporation of carbon
dioxide into organic compounds.
3. A stoma is a small pore on the surface of a plant
through which water, O2, CO2, and other gases
enter or leave the plant.
4. The C4 pathway is a carbon fixation pathway in
which CO2 is incorporated into four-carbon
compounds.
5. CAM is a carbon fixation pathway in which CO2
is incorporated into organic compounds at night
and released to enter the Calvin cycle during
the day.
MULTIPLE CHOICE
1. a
2. c
3. d
4. b
5. d
SHORT ANSWER
1. In each turn of the cycle, three molecules of ATP
and two molecules of NADPH are used.
2. CO2 + H2O + light energy→(CH2O) + O2
3. CAM plants open their stomata at night, whereas C3
and C4 plants open their stomata during the day.
4. Increasing the temperature initially accelerates the
various chemical reactions involved in photosynthesis. At higher temperatures, many of the
enzymes that catalyze these reactions become
ineffective, and the stomata begin to close.
5. The stomata would open. That would allow more
CO2 to enter the leaf from the surrounding air,
stimulating photosynthesis.
STRUCTURES AND FUNCTIONS
1. Clockwise from the top: 1 CO2, 2 PGA, 2 ATP,
2 ADP, 2 NADPH, 2 NADP1, 2 PGAL, 1 ATP, 1 ADP,
1 RuBP
Modern Biology Study Guide Answer Key
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